And amalgamating mill



(No Model.) 3 Sheets-Sheet 1.

3 M. CRAWFORD.

GRINDING AND AMALGAMATING MILL. No. 433,163.

Patented July 29, 1890.

Witnesses 3 SheetsSheet 2.

(No Model.)

M. CRAWFORD.

GRINDING AND AMALGAMATING MILL.

Patented July 29, 1890.

Invenl'or Wii'nesses 3 SheetsSheet 3,

(No Model.)

M CRAWFORD j QEENQJNQJAND AMALGAMATING MILL, NO,

Patented July 29, 1890.

lYLl/enjj m esses I the grinding surface or path O O.

UNITED STATES PATENT.

MIDDLETON ORAlVFORD, OF LIVERPOOL, ENGLAND.

GRINDING AND AMALGAMATING MILL.

SPECIFICATION forming part of Letters Patent No. 4.33,163,dated July 29,1890.

Application filed April 22, 1890. Serial No. 349,036. (No model.)Patented in England December 23, 1889, No. 20,663.

To all whom it may concern:

Be it known that I, MIDDLETON CRAWFORD, engineer, a subject of the Queenof Great Britain and Ireland, residing at 3 Oxford Street, Liverpool, inthe county of Lancaster, England, have invented a certain ImprovedGrinding and Amalgamating Mill, (for which I have applied for a patentin Great Britain, No. 20,663, dated December 23,1889,) of which thefollowing is a specification.

The principal object of my invention is to provide an apparatus whichwill very efficiently and rapidly grind ores preparatory to theseparation therefrom of gold and silver, the grinding being eifected insuch a way that while the amalgamation of the gold and silver is greatlyfacilitated the sulphur and sulphur compounds and other impurities areautomatically separated and expelled.

Figure 1 represents in vertical section, and Fig. 2 in plan,with theupper casing removed, an apparatus constructed according to myinvention;and Fig. 3 is a horizontal section taken along the line 1 2, Fig, 1,through the ore-feeding and refuse-delivering passages.

A is a case or chamber, preferably of castiron, which may convenientlybe supported 011 pillars B, and which contains the grinding surface orpath O G The part 0 of the grinding-surface is fixed in the casing A,and is consequently stationary, and the part O is rotatory, it beingkeyed onto or otherwise removably secured to the upper end of a verticalshaft or spindle D, supported at thelower end in a step-bearing E, andat the upper part in a bearing and stuffing-box E in the bottom of thecase A. The grinding surface or path O O is concave, and on it is placeda number of free balls 13, which effect the grinding operation betweenthemselves and Between the parts C and C of the grinding surface or patha space G. is left, communicating with an annular trough or recess H,formed in the bottom of the casing A to contain mercury. The bottom ofthe casing A and of the part 0 are preferably inclined, as at a a, toallow any mercury which may find its way between them to return to thetrough. A space I is provided between the bottom of the casingA and theportion O of the grinding path for the passage of water (or otherliquid) admitted thereto under pressure by a pipe K. The case A isprovided with a hood or cover L, to which the feeding-hopper H and thedischarge passage or passages N for the refuse are connected. Eyes 6 maybe screwed into the ro tating part C as shown, for convenience inhandling in putting the machine together or taking it apart.

The shaft D and portion C of the grindingpath are rotated from anysuitable prime mover by any suitable gear or driving device, such as bymeans of a driving-strap passing around a driving-pulley fast on thestrap D, or by means of gear-wheels P, as shown.

lVhen the apparatus is in operation, the material fed in at the hopper Mpasses down the pipe or passage 11 to between the balls F andgrinding-surface O C and is there ground. lVater or other liquid underpressure is passed by the pipe K into the space I beneath the rotatingportion O of the grinding-surface, the water or liquid passing thence upthrough the space G and between the grinding-balls and thegrinding-surface into the space inclosed by the casing L above, andeventually out by the outlet or outlets N, over the upper edge of whichoutlet it flows into an annular trough R, and is condnetedthence by thespout R away from the apparatus. The space in the casing between theballs and the hood or cover L allows the water to separate the gangueand impurities, which pass away with the water or liquid at the outlet,while the heavier portions likely to contain precious metal return tobetween the grinding-surface O O and the balls F to be further actedupon.

Beneath the casing A a cavity or chamber T may be provided, into which aheating agent-such as steam-may be admitted bya pipe (not shown) for thepurpose of heating the water or liquid and mercury when required. Theoutlet N is provided with partitions or baffle-plates V to prevent theheavier portions of the material being carried away with the refuse byundue agitation of the water caused by the rotating action of the part Oof the grinding-surface. The gold or other precious metal separated fromthe ore passes through the space G into the mercury contained in thetrough or recess 11, while the refuse crushed ore is carried away by thewater or liquid through the outlet above, as hereinafter described.

The mercury containing the precious metal is discharged from the troughH through the pipe \V, and is treated in the usualmanner to obtain theprecious metal.

To prevent tampering with the mercury, the

- pipe W may be fitted so that its outlet end can be turned up andsecured by a lock, as at w, which when the mercury charged with theprecious metal is to be withdrawn can be unlocked, so as to leave thepipe W free to be turned down for discharging the mercury.

X is a pipe, which can be closed by a plug or otherwise, and bywithdrawing this plug the contents of the mill can be passed oif, whendesired, to prevent clogging-for instance, when the mill stops. Bypassing an aincurrent instead of water through the apparatus it may beused for dry grinding.

I claim as my invention- 1. In a grinding-mill, the combination of freeor loose balls, an annular track or grinding-surface divided into twoparts, arranged one within the other, and separated at the bottom by anannular discharge-opening,with a mercury-container beneath it, the outerpart of the track being fixed and the inner part being adapted torotate, with means for supplying air or liquid under pressure, and abaflled outlet above, all substantially as described.

2. A grinding mill having an annular concave grinding surface or track,consisting of an outer stationary part and an inner rotating part, incombination with free or loose balls, which can come into contact witheach other and which are supported. and travel on the stationary andfixed parts of the concave track, substantially as set forth.

3. A grinding-mill having an annular concave grinding surface or'track,consisting of an outer stationar 7 part and an inner I'Ollftt. ing part,with an annular discharge-opening at the bottom between the two parts,and a trough or recess below containing mercury, in combination withfree or loose balls,which can come into contact with each other andwhich travel on the stationary and fixed parts of the concave track,substantially as set forth.

4. A grinding-mill having an annular concave grinding surface or track,consisting of an outer stationary part and an inner rotating part, withan annular discharge-opening between the two parts, a mercury trough orrecess below, and a water-supply to a chamber below the grinding-surfaceand thence to the grinding-surface, in combination with a steam or otherheating cavity below both the water-chamber and the mercury-trough, allsubstantially as described.

5. The combination of the grinding-surface, consisting of an innerrotating part and an outer fixed part, and free or loose balls travelingon the concave formed by the two, with an inclosing casing having aninlet-funnel at the top, and an overflow-discharge around this funnelcontaining partitions, and

means for supplying air, water, or other fluid w

